In a typical data center, a large collection of interconnected servers provides computing and/or storage capacity for execution of various applications. For example, a data center may comprise a facility that hosts applications and services for subscribers, i.e., customers of data center. The data center may, for example, host all of the infrastructure equipment, such as networking and storage systems, redundant power supplies, and environmental controls.
In most data centers, clusters of storage systems and application servers are interconnected via a high-speed switch fabric provided by one or more tiers of physical network switches and routers. In some network topologies, routers and switches within the fabric may be layered in a multi-staged configuration that allows for various aspects of path minimization, redundancy, and more efficient routing of network traffic within the fabric. Sophisticated data centers, referred to as distributed data centers, provide infrastructure spread throughout the world with subscriber support equipment located in various interconnected physical hosting facilities.